title: Potential high virulence for infective endocarditis in Streptococcus mutans strains with collagen-binding proteins but lacking PA expression.
abstract: OBJECTIVE
  Streptococcus mutans, an aetiologic agent of dental caries, is a pathogen for infective endocarditis (IE). We investigated strains that express collagen-binding proteins (CBPs) with further classification based on expression of the 190-kDa protein antigen (PA).
  
  
  METHODS
  Zeta-potential values of strains TW871 (CBP+/PA+) and MT8148 (CBP-/PA+), and their respective PA-defective mutant strains TW871PD (CBP+/PA-) and MT8148PD (CBP-/PA-), were analysed, as were their adhesion to and invasion of human umbilical vein endothelial cells (HUVECs). The distribution of strains from the oral cavities of 200 healthy individuals was analysed for CBP and/or PA expression and the strains were characterised for their adhesion and invasion properties.
  
  
  RESULTS
  TW871PD and MT8148PD showed significantly lower zeta-potential values than TW871 and MT8148, respectively. Collagen-binding rates were significantly higher for TW871PD than for TW871 but nearly negligible for MT8148 and MT8148PD. The adhesion and invasion rates of HUVECs were significantly higher for TW871PD than for TW871 and significantly higher for TW871 than for MT8148 and MT8148PD. The prevalence of CBP+ strains was ~10% and ~3% in the case of CBP+/PA- strains. Analyses of 200 clinical strains showed the CBP+/PA- group to have higher adhesion and invasion rates than other groups.
  
  
  CONCLUSIONS
  CBP+/PA- S. mutans strains, despite their low distribution frequency, may be highly virulent for infective endocarditis.
authors.affiliation: Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Nomura
authors.forename: S
authors.initials: S
authors.lastname: Naka
authors.forename: H
authors.initials: H
authors.lastname: Nemoto
authors.forename: M
authors.initials: M
authors.lastname: Otsugu
authors.forename: S
authors.initials: S
authors.lastname: Nakamura
authors.forename: T
authors.initials: T
authors.lastname: Ooshima
authors.forename: K
authors.initials: K
authors.lastname: Nakano
mesh_terms: D018829:Adhesins, Bacterial / Q000276:immunology* / Q000378:metabolism; D001422:Bacterial Adhesion / Q000276:immunology*; D003094:Collagen / Q000276:immunology* / Q000378:metabolism; D046508:Culture Techniques; D004697:Endocarditis, Bacterial / Q000276:immunology / Q000382:microbiology*; D006801:Humans; D018613:Microscopy, Confocal; D009055:Mouth / Q000382:microbiology*; D011485:Protein Binding / Q000235:genetics / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013295:Streptococcus mutans / Q000145:classification / Q000276:immunology / Q000472:pathogenicity*; D014774:Virulence
chemical_list: D018829:Adhesins, Bacterial; D003094:Collagen
keywords: Classification; Collagen-binding protein; Infective endocarditis; Protein antigen (PA); Streptococcus mutans